Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

04-Unexpected behaviour/errors
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afcf
Posts: 4
Joined: 25 Apr 2023, 08:54

Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by afcf »

Dear colleagues,

I am trying to simulate the in-plane cyclic behaviour of an RC shear wall connected to the foundation with two wall shoe connectors. The experiment I am trying to simulate is this one: "Experimental investigation of the response of precast concrete cladding panels with integrated connections under monotonic and cyclic loading" published on Engineering Structures.
I am assuming a simplified approach by simulating only the longitudinal reinforcement of the wall equal to the two wall rebars' diameter used in the connections and assuming that the concrete has zero tensile strength.

Regarding pushover analysis, the model captures both initial stiffness and maximum strength very well. However, when I am simulating the cyclic test, the analysis stops most of the time for lower displacement demands. The error message that appears is "elm_Tol or elm_Inv". I have checked and adjusted the tolerance as suggested in the manual for this type of error message. I have also adjusted the tolerance for the type of element I am using (Inelastic Force-based element).
Could you please give me some help? This seems to be a much simple simulation and I am not understanding where is the problem.
Best regards,
André
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seismosoft
Posts: 1184
Joined: 06 Jul 2007, 04:55

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by seismosoft »

It obviously is a convergence problem. Make sure that the model is appropriately restrained (run an eigenvalue analysis and check the modes for this) and that it can withstand the loads applied (you need to check the applied loads and the internal loads of the elements before divergence and see how they increase).
If these do not work, carry out a search in this forum, you will find numerous suggestions on how to fix convergence problems.
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afcf
Posts: 4
Joined: 25 Apr 2023, 08:54

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by afcf »

Dear Colleague,

Thanks for your suggestion. I have performed all your suggestions before posting here. I am sorry for bothering you, but I just want to know what is working out of my control in the model. The model runs the pushover analysis perfectly, but the cyclic loading has severe problems (for small displacements), which I really cannot find the issue. Could you please check my model? It is a simple model that will certainly not take too long.

The pushover and cyclic models can be downloaded at this link:
https://filesender.fccn.pt/?s=download& ... f218368e81

Thanks for your kind attention and help,
André
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z.gronti
Posts: 824
Joined: 16 Oct 2013, 08:14

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by z.gronti »

Dear afcf,

Structural failure might occur to the wall element. You should probably check the stresses and strains you get in the reinforcement and concrete.
Zoi Gronti
Seismosoft Srl.
afcf
Posts: 4
Joined: 25 Apr 2023, 08:54

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by afcf »

Dear Zoi,

Thanks for your feedback. I agree that structural failure might occur to the wall element. However, as you can see on the files, the pushover analysis is performed up to large displacements (i.e. 0.10m) without converge problems and wall element failure. The cyclic analysis stops for low displacement demands (1/5 of the pushover max. displacement), meaning the problem may not be related to structural failure. Do you agree? That is why I am kindly asking you if you think the problem is numerical, and if yes, how can I solve it? I have made all your recommendations that you have in the software manual.

Once again, thanks for your attention.
André
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by seismosoft »

You need to check the state of the member cross section, in order to understand if it is a structural failure or not. This can be done by checking the curvatures, but mainly by setting stress point, so that to understand if the member can sustain more loads or not.
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afcf
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Joined: 25 Apr 2023, 08:54

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by afcf »

I have checked it. The failure occurs for very small displacements. The stress levels are insignificant, and the curvature is insufficient to justify the analysis stops. Note that the analysis stops after the first peak target displacements and is near zero, which is quite strange. Could you please help me clarify if there is any bug in my model or the software?
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seismosoft
Posts: 1184
Joined: 06 Jul 2007, 04:55

Re: Problems in simulating cyclic behaviour of RC shear wall with wall shoes connector

Post by seismosoft »

Unfortunately, we are a small company with limited resources, and we cannot check the specific models for every user that we have, unless of course he/she is a commercial customer (we have literally thousands of academic users). There are numerous posts in the forum on how to overcome numerical instabilities. Also check the specific section on the User's Manual (Appendix A, Tips to Solve Convergence Problems).
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